Air seal for boiler drums



Jan. 23, M H. KUHNER AIR SEAL FOR BOILER DRUMS Filed OCL. l5, 1931 7. f@` Y /9 MAX. H. [fz/HAIER BY M? ATTORNEY Patented Jan. 23, 1934 PATENT OFFICE ATR SEAL FOR BOILER DRUMS Max H. Kuhner, Cornwells Heights, Pa., assignor,

by mesne assignments, to Riley vStoker Corporation, Worcester, Mass., a corporation of Massachusetts Application October 15,

4 Claims.

This invention relates to air seals for boiler drums, and more particularly to a construction arranged to prevent leakage of air into the furnace around the drums of water tube boilers.

One form of water tube boiler comprises a plurality of drums or shells connected by banks of water tubes. One or more of the drums is usually anchored to the supporting frame work, while the other drums are free to move and thus allow the tubes to expand or contract as the temperature varies. When the ends of a drum extend outside the walls of the furnace, it is necessary to provide a clearance space between the drum and the furnace wall, so that this movement of the drum may take place. Since the interior of the furnace chamber is ordinarily at a pressure slightly below that of the atmosphere, there is a decided tendency for air to leak into the furnace through the clearance space. Any such leakage reduces the efficiency of the boiler and furnace, and is highly undesirable.

It is accordingly the main object of my invention to provide a simple and effective construction Which will prevent leakage of air into a furnace between a boiler drum and the furnace wall through which it extends.

It is a further object of the invention to provide an air seal 'which will allow the boiler drum to move freely relative to the furnace wall, and which will at all times prevent air leakage between these parts. t

It is a further object of the invention to provide an air seal which will remain tight regardless of the longitudinal expansion of the drum itself.

It is a further object to provide an air seal which is simple and inexpensive to manufacture and install.

It is a further object to provide a simple and effective means for holding heat insulating material in place on they ends of the drum. n

With these and other objects in view, as will be apparent to those skilled in the art, my invention resides in the combination of parts set forth in the specication and covered by the claims appended hereto.

In accordance with my invention I provide a.

1931. Serial No. 569,017

wall. The inner diameter of the ring is preferably slightly greater than the outer diameter of the drum, so that the drum may expand freely lengthwise without moving the ring, and air leakage between these parts may be prevented by flexible packing. This packing may be held in place by a sleeve formed integral with the sealing ring. Heat insulating material is preferably provided on the end of the drum, and this material may be held inV place by wires. The ends of the wires may be connected to the sealing ring.

Referring to the drawing illustratingv one embodiment of the invention, and in which like reference numerals indicate like parts,

Fig. l is an elevation showing a portion of the outside of a furnace wall having a boiler drum extending therethrough;

Fig. 2 is an enlarged section on the line 2-2 of Fig. 1;

Fig. 3 is a perspective View of a clamp; and

Fig. '4 is a perspective view of a sealing ring sector.

The embodiment illustrated in the drawing comprises a vertical furnace wall 10 constructed of suitable refractory and heat insulating material, and protected on the outside by a sheet metal casing 11. A horizontal cylindrical boiler drum or shell 12 is mounted inside the furnace with one end projecting outwardly through a circular opening 14 in the wall 10. This opening is somewhat larger in diameter than the drum. The drum is supported by banks of Water tubes 15 and 16 which are connected to other drums (not shown)` to form a complete water tube boiler of well known construction. The end of the drum 12 is closed by a head 18 fastened to the cylindrical portion of the drum by rivets 19, as is common in the art.

It will now be understood that the tubes 15 and 16 will increase in length when heat is applied to them for the generation of steam, and this will cause the drum 12 to move in a direction perpendicular to its axis. The drum itself will also expand appreciably in an axial direction. The opening 14 is suiciently large to permit these movements of the drumwithout interference with the wall l0, but it is necessary to provide some means to seal the opening around the drum and thus prevent leakage of air into the furnace.

The sealing means illustrated in the drawing comprises a ring 21 in the form of a fiat annular plate surrounding the drum 12 and in contact with the outer surface of the wall casing 11. This isy j This insulation is held inrplace by wires 36A fasring 21 has an outer diameter appreciably greater than the opening 14, and an inner diameter very slightly greater than the outside diameter of the drum. This slight clearance is preferably allowed between the ring and the drum, so that the latter may expand axially withouttending to move the ring away from the wall.

I -provide' suitable means tohold the ring in close'contact with the wall, and for this purposeI have shown a series of clamps 22 spaced abouttheA periphery of the ring and each fastened to'the'f wall casing 11 by a bolt 23. The headsvof the bolts 23 are shown welded to the inside of thecasing at 24 (Fig. 2) to hold thern firinlyin'place."

Each clamp 22 is shaped as a rectangular-body-1v having a bolt hole 26 therethrough and a rib`27 at one edge for contact with the Wall. The bolts 23 are arranged in a circle substantially larger in diameter than the ring 21 so that they will not interfere with the sliding movement of the ring.

s .'Ihese boltsare tightened only sufcientlyto ene fsure'contact between the ring and the casing 11'1A "andl thering .free to slide in a vertical plane along the surface of the' casingy asthe drum' 12 moves relative to the furnace wall;

' While 'the sealing ring 21 may be formed as a" single unitary'niernber, I preferito construct this' ring in sections `for convenience inY assernbly.l ,Threevsections are shown in the illustrated em- Vbodirnent,l and 'they are fastened together by .bolts 29 extending through outwardly extending' ears or lugsV 30 onthe ring sections. Y y In order to prevent any air leakage through the slight clearancespace between the ringfll andV the druin 12, I preferably provide a st iitable flexible packing material such as asbestosrope 32kv surroundingithe drum outside the ring. y Thisl rope 32 is held in place bya cylindrical project-Vj ing shelf orsleeve 33 formed integral" withv the' ring 21.` This cylindrical portion 33 islarger in" diameter than the drum, and the space between thesepartsv is occupied by the asbestos packing.

` A layer 3.5 of'a suitable heat insulating `Arnate- A rial, such asl 85% magnesia, is preferably Aplaced against jouter surface jor" the drurnhead 18.A

tened at their 'ends to the sleeve 33, holes 37be-I v tractionl ofthe tubesl and i6,A andthe 'sealingVVIV will slide under Ithe clairps y22, while at all:Y

vent leakage or" air into the furnace. 'may expand freelyv in a lengthwise direction relaing provided'therein for this purpose. A coating ling `plaster 39 'may Abe applied not onlyfprovides a smooth finish for thej`drum` head but also serves to noidthe `pacl ing`32 in rposition'within vthe sleeve SB? The loperation ofthe invention will now be apparentfrorh the above disclosure. Thefdruni 12 is free to move as a result of expansion or rconring'2l times contacting with the wall casing'ijltopretive to the sealing ring, and `leakage between This gz-laster*39 is The drurn out attention.

Having thus described my invention, what I claim as new and desire to secure by Letters ArPatent is,

1. The combination with a refractory furnace wallhaving'an outer sheet metal casing, the Wall Vand casing having' a circular-opening there- 'thro`ugh,: a4 horizontal boiler drum smaller in diameter than the opening and extending through the'v opening, a sealing ring surrounding lthe drum outside the Wall, the inner diameter of thefsea'ling ring being slightly larger than the oiiteridiameter of the drum, means to hold the sealing ring in sliding contact with the casing, nn ular sleeve-extending outwardly from the nd spaced'irorn the drurn,' and flexible V'packing means located -in the space between the sleeve and' the-drum to prevent leakage of air ybetween the druni'a'nd sealing ring. l "-"2.4"Ihe combination with a refractory furnace wall vtrailing-an outer sheet metal casing, the wall andczising' having a circular opening thererjthr`ofugh aihorizontalr boiler drum smaller in diameter .thanI the lopening and extending A'thro'ugh the "opening, a sealing ring surrounding the drum outside the wall, the inner diameter of "the vsal-ing vrring" beingY slightly larger than the '-cut'er'diameter of the drum, a series oi spaced "clarnps-bolted= tothe casing around the ring fandserving to hold the ring in sliding contact with the casing;y anannular sleeve extending outwardly forn ring and spaced from the drum, *and rie ble packing means located in the space e'tweerrthe 'sleeve and drum to prevent leakage 'of "airbetween tliefdrurn and sealing ring.

3. The combination with a iurnace wall having a V"c' cular opening therethrough, a horizontal boil' 'ruin 'srn'aller in diameter than the opening extendingl through the opening, a sealing -su'rroundr-ig 'the drurn voutsideV the wall, means to hold the sealing insliding contact outside-oif'the` wall, an annular sleeve 5 the pacebetwe'en the sleeve and the drum, and plaster on the drum adjacent to the packing 'leansto'hold the packing means in place.

Y4'. The'conibination with' a furnace' wall having a Ycir'cularopeningftherethrcugh, a horizontal boiler druml smaller in diameter than the opening ending 'through the opening, a sealing ring Vsurrcun'dingFthe' drum outside the wall, rneans to hold the sealing ring in sliding Contact "wit-h'theoutsideof Vthe wall, an annular sleeve ex.- tend'in'g wardlyfrom the ring and spaced from the idrinn, -'iiexible Vpacking means locatedin the Lthese parts is prevented by the' packingSZ.fThisWspacfbetween the sleeve andthe drum; plaster packing is'perrnanently protected and held in' place by Vthe cylindrical portion 33. 4 35 form a simple and effective r11/leans*for/"supporting the insulation 35 on the drum head. This insulation isr of a somewhat yielding nature so The wires? on thedrum adjacent to thepacliing means to hold'fthe packing means in place, and wires con- 1inected"at'their' ends to the annular sleeve'and arranged to reinforcethe plaster. 

